A Subscriber Identification Module (SIM) card of a terminal is used to store code information corresponding to a communication number. When the code information passes verification of a network operator, the SIM card is allowed to access a communication network of the operator, such that a user of the terminal can use the communication number to make phone calls, send messages, etc.
Conventionally, when a terminal is used to write the code information into a SIM card, the following information writing method may be performed by the terminal. First, the terminal connects to a communication network of an operator. When it is needed to write certain code information into a SIM card of the terminal, the network operator sends the code information to an Over-the-Air-Technology (OTA) gateway. The OTA gateway converts the code information into an OTA short message and then sends the OAT short message to a short message service center. The short message service center then sends the OAT short message to the terminal. The terminal sends the OTA short message to the SIM card via a dedicated interface. Finally, the SIM card stores the code information according to the received OTA short message. The dedicated interface is an interface specially configured for the terminal to send the OTA short message to the SIM card.